In my talk I am 1) discussing philosophical concepts of privacy, especially Hannah Arendt's philosophy. I am 2) explaining why in a liberal-democratic system we need to protect our privacy and 3) what we can morally do to prevent catastrophes such as a totalitarian system from happening again. With Hannah Arendt's arguments and her analysis of totalitarian systems in mind, I am referring to three examples from today's privacy discussions: cybermobbing, Behavioral Advertising and secret services.

That our privacy is at stake is not just a problem since the 2013 revelations of Edward Snowden. The 20th century philosopher Hannah Arendt is an important source to understand what `privacy' means and why we need to protect it. In my talk I am going to explain what Arendt understood as `private' throughout her work, and how her reasons to claim the protection of the private realm were connected with her analysis of the totalitarian systems in the 20th Century. In my contribution I am first discussing philosophical concepts of privacy, with a focus on Hannah Arendt's philosophy. Second, I am arguing why in a liberal-democratic system we need to protect our privacy. The third step will be to reason what we can morally do to prevent catastrophes such as a totalitarian system from happening again.Being a philosopher, I am going to make the philosophical — and in part legal — claims and preconditions understandable for a larger public. To prevent "what never ought have happened" from happening again we should, following Arendt, never refuse to judge about what is happening around us. I apply Arendt's framework of moral judging by examples to three cases from today's privacy discussions, Cybermobbing, Behavioral Advertising and secret services.